FIGS. 7, 8A and 8B illustrate structures of a conventional optical disk of a recordable type. FIG. 7 illustrates the structure of an optical disk 710 including at least one pre-recorded region 701 and at least one recordable region 703. The pre-recorded region 701 is an unalterable region containing information which has been recorded in the form of embossed pits. The recordable region 703 has a grooved structure.
FIG. 8A illustrates the structure of an information track in the pre-recorded region 701. FIG. 8B illustrates the structure of an information track in the recordable region 703. As illustrated in FIGS. 8A and 8B, an information track 801 in the pre-recorded region 701 and an information track 802 in the recordable region 703 are wobbled. A wobbling frequency component of the information tracks 801 and 802 is extracted for realizing synchronization with a recording clock used for recording information in a portion of the recordable region 703. Address information indicated by reference numeral “804” of FIG. 8A or reference numeral “803” of FIG. 8B is embedded between the information tracks.
The address information (e.g., address information 803 or 804) is embedded so as to synchronize with each ECC (error correcting code) block. By detecting an address signal from the address information, a reproduced position on the optical disk can be known. By recording information on the optical disk in synchronization with the detected address signal, an information recording in synchronization with an ECC block can be attained. The techniques concerning the address signal can be found in a DVD-R standard handbook or the like.
FIG. 9 illustrates a conventional optical disk recording device 900. The optical disk recording device 900 includes a head unit 902, a recording clock synchronization signal (RCSS) reproducing section 903, a recording clock (RC) generation section 904, a data recording section 905, an address detection section 906, a recording control section 907, a tracking error signal (TES) generation section 908, a servo control section 911, and an access control section 912. An optical disk 901 is rotated by a disk motor (not shown).
A light beam emitted from the head unit 902 is reflected on the optical disk 901. The head unit 902 outputs a signal which is in accordance with the reflected light from the optical disk 901. Based on the output of the head unit 902, the TES generation section 908 outputs a tracking error signal representing a deviation of a focusing spot of the light beam from an information track. Based on the tracking error signal output from the TES generation section 908, the servo control section 911 controls the head unit 902 and a focal lens (not shown) mounted on the head unit 902 so that the focusing spot of the light beam is positioned on the information track.
The RCSS reproducing section 903 is used for extracting a wobbling frequency component of the information track. The RC generation section 904 generates a recording clock so as to have a frequency which is a multiple of the frequency component. The address detection section 906 is used for receiving a signal reproduced by the head unit 902 and detecting an address from the address information such as address information 803 of FIG. 8B or address information 804 of FIG. 8A. The recording control section 907 is used for generating a signal with which to start/stop a data recording in accordance with the address detected by the address detection section 906. The data recording section 905 is used for sending to the head unit 902 data to be recorded on an information track of the optical disk 901 in synchronization with a recording clock, which is generated by the RC generation section 904 based on a signal from the recording control section 907.
FIG. 10 is a flow chart illustrating recording operations in the conventional optical disk recording device 900 for recording information in a portion of the recordable region 703 immediately after the pre-recorded region 701. As illustrated in FIG. 10, in order to record information in the portion of the recordable region 703 immediately after the pre-recorded region 701, the access control section 912 sends to the servo control section 911 an instruction to access the pre-recorded region 701 at step S1001. According to the instruction from the servo control section 911, the head unit 902 moves along a radial direction of the optical disk 901 so as to be positioned in the pre-recorded region 701 on the optical disk 901.
At step S1002, the RCSS reproducing section 903 extracts a wobbling frequency component of an information track in the pre-recorded region 701. The RC generation section 904 controls the recording clock so as to have a frequency which is a multiple of the frequency component.
At step S1003, the address detection section 906 detects an address on the optical disk 901 based on a reproduced signal. The recording control section 907 waits until the focusing spot of the light beam reaches the portion of the recordable region 703 immediately after the pre-recorded region 701 based on the address detected by the address detection section 906.
After the focusing spot of the light beam has reached the recordable region 703, the control proceeds to S1004. The recording control section 907 sends a signal to the data recording section 905. The data recording section 905 sends to the head unit 902 a data to be recorded on an information track of the optical disk 901 in synchronization with a recording clock which is generated by the RC generation section 904 based on the signal from the recording control section 907.
In recent years, recordable optical disks have come into wide use. An optical disk structure such that information which is specific to each optical disk is recorded in an unalterable pre-recorded region has been proposed in consideration of copyright protection.
In such an optical disk, a pre-recorded region does not include any information which can be used for recording clock synchronization (i.e., a wobbling structure of the above-described information tracks 801 or 802) in order to stably reproduce the aforementioned optical disk-specific information. Therefore, in the conventional optical disk and optical disk recording device, when recording information in a portion of a recordable region immediately after the pre-recorded region, the recording clock cannot be established with a prescribed frequency since no information for synchronizing the recording clock is provided in the pre-recorded region, so that it is impossible to record information at a beginning portion of the recordable region.